LOR #155

I got LOR #155 *I think* when unload acpi_video while testing some of 
jhb's patches.

acpi_video0: detached
lock order reversal: (sleepable after non-sleepable)
 1st 0xc104e8c8 mt_zone (UMA zone) _at_ /usr/src/sys/vm/uma_core.c:2452
 2nd 0xc2424d34 user map (user map) _at_ /usr/src/sys/vm/vm_map.c:2993
KDB: stack backtrace:
witness_checkorder(c2424d34,9,c062abe6,bb1,cc9dbaac) at 
witness_checkorder+0x5aa
_sx_xlock(c2424d34,c062abe6,bb1,1000001,cc9dbaac) at _sx_xlock+0x3c
vm_map_lookup(cc9dbaac,0,1,cc9dbab0,cc9dbaa0,cc9dbaa4,cc9dba87,cc9dba88) 
at vm_map_lookup+0x24
vm_fault(c2424cf0,0,1,0,c25ed1a0) at vm_fault+0x63
trap_pfault(15) at trap_pfault+0x12c
trap(8,28,28,0,c104e8c0) at trap+0x37a
calltrap() at calltrap+0x5
--- trap 0xc, eip = 0xc05a8ec8, esp = 0xcc9dbc08, ebp = 0xcc9dbc1c ---
uma_zfree_internal(0,1,3) at uma_zfree_internal+0xb8
malloc_uninit(c078f020,c078ee1c,0,cc9dbc70,c04aebc2) at 
malloc_uninit+0xb3
linker_file_unload(c2049b00,0,0,c25ed1a0,c25ebadc) at 
linker_file_unload+0x2f8
kern_kldunload(0,cc9dbd04,2,0,3) at kern_kldunload+0x68
syscall(3b,3b,3b,5,bfbfe9de) at syscall+0x166
Xint0x80_syscall() at Xint0x80_syscall+0x1f
--- syscall (444, FreeBSD ELF32, kldunloadf), eip = 0x280ab48b, esp = 
0xbfbfe464, ebp = 0xbfbfe8a8 ---
KDB: enter: witness_checkorder
[thread pid 717 tid 100061 ]
Stopped at      kdb_enter+0x2c: leal    0(%esi),%esi
db> bt
Tracing pid 717 tid 100061 td 0xc25ed1a0
kdb_enter(c05ff2df,9,c062abe6,bb1,cc9dbaac) at kdb_enter+0x2c
_sx_xlock(c2424d34,c062abe6,bb1,1000001,cc9dbaac) at _sx_xlock+0x3c
vm_map_lookup(cc9dbaac,0,1,cc9dbab0,cc9dbaa0,cc9dbaa4,cc9dba87,cc9dba88) 
at vm_map_lookup+0x24
vm_fault(c2424cf0,0,1,0,c25ed1a0) at vm_fault+0x63
trap_pfault(15) at trap_pfault+0x12c
trap(8,28,28,0,c104e8c0) at trap+0x37a
calltrap() at calltrap+0x5
--- trap 0xc, eip = 0xc05a8ec8, esp = 0xcc9dbc08, ebp = 0xcc9dbc1c ---
uma_zfree_internal(0,1,3) at uma_zfree_internal+0xb8
malloc_uninit(c078f020,c078ee1c,0,cc9dbc70,c04aebc2) at 
malloc_uninit+0xb3
linker_file_unload(c2049b00,0,0,c25ed1a0,c25ebadc) at 
linker_file_unload+0x2f8
kern_kldunload(0,cc9dbd04,2,0,3) at kern_kldunload+0x68
syscall(3b,3b,3b,5,bfbfe9de) at syscall+0x166
Xint0x80_syscall() at Xint0x80_syscall+0x1f
--- syscall (444, FreeBSD ELF32, kldunloadf), eip = 0x280ab48b, esp = 
0xbfbfe464, ebp = 0xbfbfe8a8 ---
db> 
-- 
Anish Mistry